Extension of Definition Interval for C-Curves

By analyzing the properties of higher degree derivatives of C-curve basis, we extend α from 0,π to 0,2π in C-Bézier curves,and show α can be larger while elevating the order of C-B-spline curves. Moreover, the positivity of C-Bézier basis and C-B-spline basis is also discussed. The results obtained can enhance the modeling power of C-curves.